There were declines on achievement tests between 1972 and 1980. This study, the first part of A Study of High School Excellence, was designed to document changes in the achievement of high school seniors between 1972 and 1980, to identify the school and student factors related to these changes, and to examine the policy implications of the…

Since the mean score for a sample composed of several subgroups can be viewed as the sum of the mean of each subgroup weighted by the proportional size of the subgroup, then the mean change in a time period--in this case, from 1972 to 1980--is the sum of the differences between the means for each subgroup, with each mean weighted by its…